Internal Model-Based Current Control of the RL Filter-Based Voltage-Sourced Converter

Power system operates close to its operational limit to achieve a higher level of utilization of the grid infrastructure. As a result, its transient behavior is of great importance to prevent violation of the operation limits. This paper proposes an internal model control (IMC)-based approach for voltage-sourced converters (VSC) to improve their dynamic behavior. This IMC controller is designed based on a detailed model of the VSC. The proposed control approach has superior performance, i.e., faster step response and less overshoot, and higher axes decoupling than the conventional dq-current control method. The proposed IMC-based controller has a straightforward design procedure, and can be implemented using simple PI and PID controllers. Several case studies are presented to evaluate and compare the transient performance of the IMC-based controller with conventional dq current control subsequent to step changes in the set points of direct and quadrature axes current, single-phase fault, and three-phase fault.